<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script src="../js/vue.js"></script>
    <div id="app">
        <p>First name: <input type="text" v-model="firstName"></p>
        <p>Last name: <input type="text" v-model="lastName"></p>
        <p>fullname:{{fullname}}</p>
        <button @click="change">改变fullname</button>
    </div>
    
    <script>
        let vm = new Vue({
            el: "#app",
            data: {
                firstName: '',
                lastName: ''
            },
            methods: {
                change() {
                    this.fullname = 'Harry Potter';
                }
            },
            computed: {
                fullname: {
                    get: function () {
                        return this.firstName + ' ' + this.lastName;
                    },
                    set: function (newVal) {
                        var arr = newVal.split('');
                        this.firstName = arr[0];
                        this.lastName = arr[1];
                    }
                }
            }
        })
    </script>
</body>

</html>